It's easy.
First you need to notice that the cables and barrels is color coded. You need to reproduce this so you get the cables back in the right slot. Colored electrical tape works well. Remember you have to mark BOTH the barrel and cable.
Next take a small flat bladed screwdriver and slowly work the jaws of the clamp apart. You want to get it a minimal distance apart then slip the cable out. Once you have all three out you can separate the two pieces.
I wouldn't call it easy. The clamp jaws you need to spread are a lightweight cast material. You need to be really careful not to split when opening or reclamping. I had varied success. I was able to use an expoxy held with a zip tie until it cured for one that split on reclamping.
